I'm having trouble finding out any errors in a ray diagram.
The question is as follows:
A ray of light falls normally on the curved face of a semi-circular plastic block, it hits the horizontal face of the block at an angle of incidence of 30 degrees, and emerges to air forming an angle of 40 degrees with the normal.
This drawing carries 6 marks, but the teacher circled a part of the following drawing and it fetched 5.5 marks.
However, I can't spot any errors. Are there are any issues in this diagram? Please let me know in either case, if you think there are, or aren't.